Maven plugin fails to set the classpath

[luontola]

Without Maven plugin:

[INFO] --- maven-antrun-plugin:1.7:run (retrolambda-classes) @ jumi-core ---
[INFO] Executing tasks

main:
     [exec] Retrolambda 1.1.2
     [exec] Bytecode version: 51 (Java 7)
     [exec] Input directory:  C:\DEVEL\Jumi\jumi\jumi-core\target\classes
     [exec] Output directory: C:\DEVEL\Jumi\jumi\jumi-core\target\classes
     [exec] Classpath:        C:\DEVEL\Jumi\jumi\jumi-core\target\classes;C:\Users\ORFJackal\.m2\repository\fi\jumi\jumi-actors\0.1.196\jumi-actors-0.1.196.jar;C:\DEVEL\Jumi\jumi\jumi-api\target\jumi-api-0.5-SNAPSHOT.jar;C:\Users\ORFJackal\.m2\repository\junit\junit\4.11\junit-4.11.jar;C:\Users\ORFJackal\.m2\repository\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Users\ORFJackal\.m2\repository\io\netty\netty\3.5.5.Final\netty-3.5.5.Final.jar;C:\Users\ORFJackal\.m2\repository\commons-io\commons-io\2.4\commons-io-2.4.jar;C:\Users\ORFJackal\.m2\repository\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar;C:\Users\ORFJackal\.m2\repository\cglib\cglib-nodep\2.2.2\cglib-nodep-2.2.2.jar;C:\Users\ORFJackal\.m2\repository\com\google\code\findbugs\jsr305\2.0.1\jsr305-2.0.1.jar
     [exec] Saving lambda class: fi/jumi/core/ipc/buffer/MappedByteBufferSequence$$Lambda$1
     [exec] Saving lambda class: fi/jumi/core/network/NettyNetworkClient$$Lambda$1
     [exec] Saving lambda class: fi/jumi/core/network/NettyNetworkServer$$Lambda$1
     [exec] Saving lambda class: fi/jumi/core/util/timeout/InitialMessageTimeout$$Lambda$1
[INFO] Executed tasks

With Maven plugin:

[INFO] --- retrolambda-maven-plugin:1.2.0:process-main (default) @ jumi-core ---
[INFO] Retrieving the Retrolambda JAR
[INFO] Configured Artifact: net.orfjackal.retrolambda:retrolambda:1.2.0:jar
[INFO] Copying retrolambda-1.2.0.jar to C:\DEVEL\Jumi\jumi\jumi-core\target\retrolambda.jar
[INFO] Processing classes with Retrolambda
[INFO] Executing tasks

main:
     [exec] Retrolambda 1.2.0
     [exec] Bytecode version: 51 (Java 7)
     [exec] Input directory:  C:\DEVEL\Jumi\jumi\jumi-core\target\classes
     [exec] Output directory: C:\DEVEL\Jumi\jumi\jumi-core\target\classes
     [exec] Classpath:        C:\DEVEL\Jumi\jumi\jumi-core\target\classes
     [exec] WARNING: Method '<clinit>' of interface 'fi/jumi/core/drivers/DriverFinder' is non-abstract! This will probably fail to run on Java 7 and below. If you get this warning _without_ using Java 8's default methods, please report a bug at https://github.com/orfjackal/retrolambda/issues together with an SSCCE (http://www.sscce.org/)
     [exec] Saving lambda class: fi/jumi/core/ipc/buffer/MappedByteBufferSequence$$Lambda$1
     [exec] Error! Failed to transform some classes
     [exec] java.lang.RuntimeException: java.lang.TypeNotPresentException: Type org.jboss.netty.channel.ChannelPipelineFactory not present
     [exec]     at net.orfjackal.retrolambda.LambdaReifier.reifyLambdaClass(LambdaReifier.java:34)
     [exec]     at net.orfjackal.retrolambda.LambdaUsageBackporter$InvokeDynamicInsnConvertingMethodVisitor.backportLambda(LambdaUsageBackporter.java:110)
     [exec]     at net.orfjackal.retrolambda.LambdaUsageBackporter$InvokeDynamicInsnConvertingMethodVisitor.visitInvokeDynamicInsn(LambdaUsageBackporter.java:102)
     [exec]     at org.objectweb.asm.ClassReader.readCode(ClassReader.java:1438)
     [exec]     at org.objectweb.asm.ClassReader.readMethod(ClassReader.java:1017)
     [exec]     at org.objectweb.asm.ClassReader.accept(ClassReader.java:693)
     [exec]     at org.objectweb.asm.ClassReader.accept(ClassReader.java:506)
     [exec]     at net.orfjackal.retrolambda.LambdaUsageBackporter.transform(LambdaUsageBackporter.java:19)
     [exec]     at net.orfjackal.retrolambda.Main$1.transform(Main.java:40)
     [exec]     at net.orfjackal.retrolambda.BytecodeTransformingFileVisitor.visitFile(BytecodeTransformingFileVisitor.java:25)
     [exec]     at net.orfjackal.retrolambda.BytecodeTransformingFileVisitor.visitFile(BytecodeTransformingFileVisitor.java:11)
     [exec]     at java.nio.file.Files.walkFileTree(Files.java:2667)
     [exec]     at java.nio.file.Files.walkFileTree(Files.java:2739)
     [exec]     at net.orfjackal.retrolambda.Main.main(Main.java:38)
     [exec] Caused by: java.lang.TypeNotPresentException: Type org.jboss.netty.channel.ChannelPipelineFactory not present
     [exec]     at sun.invoke.util.BytecodeDescriptor.parseSig(BytecodeDescriptor.java:85)
     [exec]     at sun.invoke.util.BytecodeDescriptor.parseMethod(BytecodeDescriptor.java:63)
     [exec]     at sun.invoke.util.BytecodeDescriptor.parseMethod(BytecodeDescriptor.java:41)
     [exec]     at java.lang.invoke.MethodType.fromMethodDescriptorString(MethodType.java:911)
     [exec]     at net.orfjackal.retrolambda.LambdaReifier.toMethodType(LambdaReifier.java:98)
     [exec]     at net.orfjackal.retrolambda.LambdaReifier.callBootstrapMethod(LambdaReifier.java:72)
     [exec]     at net.orfjackal.retrolambda.LambdaReifier.reifyLambdaClass(LambdaReifier.java:30)
     [exec]     ... 13 more
     [exec] Caused by: java.lang.ClassNotFoundException: org.jboss.netty.channel.ChannelPipelineFactory
     [exec]     at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
     [exec]     at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
     [exec]     at java.security.AccessController.doPrivileged(Native Method)
     [exec]     at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
     [exec]     at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
     [exec]     at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
     [exec]     at sun.invoke.util.BytecodeDescriptor.parseSig(BytecodeDescriptor.java:83)
     [exec]     ... 19 more